Patient-Specific Partial Knee Guides And Other Instruments

ABSTRACT

A patient-specific unicompartmental tibial guide has a patient-specific body with an inner surface. The inner surface is preoperatively configured to nestingly conform and mate in only one position with an anterior portion and a proximal portion of a tibial bone of a specific patient. The tibial guide includes a vertical resection channel having a variable width preoperatively configured for guiding a vertical resection through the proximal portion of the tibial bone.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 13/097,145, filed Apr. 29, 2011. This application claims thebenefit of Provisional Application No. 61/542,277, filed Oct. 10, 2011.The disclosures of the above applications are incorporated herein byreference.

INTRODUCTION

The present teachings provide various patient-specific guides and otherinstruments for partial or unicompartmental knee arthroplasty. Variouspatient-specific femoral and tibial partial knee guides and relatedinstruments are provided. The patient-specific guides are designed andconstructed preoperatively based on three-dimensional digital images ofthe patient's knee joint and/or other joints. The digital images of thepatient's joint can be reconstructed from medical scans of the patientusing commercially available CAD (Computer Aided Design) and/or otherimaging software.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

The present teachings provide various patient-specific surgical kits forunicompartmental or partial knee arthroplasty. The surgical kit caninclude a patient-specific unicompartmental tibial guide that has apatient-specific body with an inner surface. The inner surface ispreoperatively configured to nestingly conform and mate in only oneposition with an anterior portion and a proximal portion of a tibialbone of a specific patient. The tibial guide includes a verticalresection channel having a variable width preoperatively configured forguiding a vertical resection through the proximal portion of the tibialbone. In some embodiments, the variable width varies in a coronal planerelative to the patient, or in an axial plane or in both coronal andaxial planes.

In some embodiments, the surgical kit includes a patient-specificunicompartmental tibial guide including a vertical resection channelhaving a first width formed between first and second flanges of thetibial guide. The surgical kit includes at least one cutting inserthaving a first plate receivable in the vertical resection channel andchanging the first width of the resection channel to a second widthsmaller than the first width. A plurality of cutting inserts havingdifferent widths can be included in the surgical kit.

The present teachings also provide various methods for unicompartmentalknee arthroplasty. In one embodiment, the method includes mounting apatient-specific tibial guide on a tibial bone, and nestingly mating andregistering a patient-specific inner surface of the tibial guide onto acorresponding anterior surface of the tibial bone and a correspondingproximal surface of a proximal plateau of the tibial bone. A verticaltibial resection of the proximal plateau can be made through a verticalresection channel of the tibial guide. The vertical resection channelhas variable width along an anatomic plane of the patient.

In another embodiment, the method includes mounting a patient-specifictibial guide on a tibial bone and selecting one of a plurality ofcutting inserts having different widths. A plate extending from thecutting insert is inserted into a vertical resection channel and changesthe width of the vertical resection channel to a reduced width. Avertical tibial resection of the proximal plateau can be made throughthe reduced width.

In another embodiment, the method includes mounting a patient-specificfemoral guide on a femoral bone and coupling a tibial sizing gauge to adistal opening of a guiding formation of the femoral guide. The tibialgap is measured using the tibial sizing gauge and a tibial resectionblock is coupled to the tibial sizing gauge. A vertical resection of thetibia is made at a distance determined by the tibial sizing gauge.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is a perspective view of a patient-specific tibial guideaccording to the present teachings and showing a coronal view of acutting guide;

FIG. 1A is a perspective view of another patient-specific tibial guideaccording to the present teachings and showing a coronal view of acutting guide;

FIG. 2 is a perspective axial view of another patient-specific tibialguide according to the present teachings and showing an axial view of acutting guide;

FIG. 2A is a detail of a vertical resection guiding surface of apatient-specific tibial guide according to the present teachings;

FIG. 3 is an environmental perspective view of the patient-specifictibial guide of FIG. 1;

FIG. 4 is a perspective view of a patient-specific tibial guideaccording to the present teachings;

FIGS. 5-7 are various perspective views of a patient-specific femoralguide in use with a tibial gauge according to the present teachings;

FIG. 8 is an environmental view of the patient-specific femoral guideand tibial gauge of FIG. 7 shown in use with a tibial block;

FIG. 9 is a perspective view of an instrument assembly showing thecoupling of the tibial gauge to the tibial block of FIG. 8;

FIG. 10 is a perspective view of the patient-specific femoral guide ofFIG. 5 shown with a femoral drill template; and

FIG. 11 is a perspective view of an exemplary unicompartmental kneereplacement implant assembly.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings. Example embodiments are provided so that thisdisclosure will be thorough, and will fully convey the scope to thosewho are skilled in the art. Numerous specific details are set forth suchas examples of specific components, devices, and methods, to provide athorough understanding of embodiments of the present disclosure. It willbe apparent to those skilled in the art that specific details need notbe employed, that example embodiments may be embodied in many differentforms and that neither should be construed to limit the scope of thedisclosure. In some example embodiments, well-known processes,well-known device structures, and well-known technologies are notdescribed in detail.

The present teachings provide various patient-specific guides andassociated instruments for partial or unicompartmental kneearthroplasty. Various patient-specific femoral and tibial alignmentguides, drill templates, cutting inserts and associated instruments areprovided. The patient-specific guides are designed and constructedpreoperatively based on three-dimensional digital images of thepatient's knee joint and/or other joints. The digital images of thepatient's joint can be reconstructed from medical scans of the patientusing commercially available CAD and/or other imaging software.

In the context of the present teachings, patient-specific guides,including alignment and/or resection guides are generally configured tomatch the anatomy of a specific patient in one or more respects. Eachpatient-specific guide has a patient-specific anatomy-engaging surfacethat is configured as a mirror or negative or complementary surface thatcan conformingly contact and match a corresponding bone surface of thepatient (with or without cartilage or other soft tissue).

In this respect, the patient-specific guide can nestingly mate andregister in only one position with the corresponding joint surface (withor without articular cartilage) of the specific patient replicatingcomplementarily at least a portion of the joint surface. Apatient-specific alignment guide can include custom-made(patient-specific) guiding formations, such as, for example, guidingholes for sutures or K-wires or for inserting pins or other fasteners inconfigurations determined by a surgeon-approved pre-operative plan. Insome embodiments, patient-specific alignment guides can also beconfigured as patient-specific resection guides and includepatient-specific cutting guides, such as cutting slots, edges or otherguiding formations for guiding a cutting tool to perform preoperativelyplanned resections of the joint.

The patient-specific guides can be designed preoperatively usingcomputer-assisted image methods based on three-dimensional images of thepatient's knee anatomy reconstructed from MRI, CT, ultrasound, X-ray, orother three- or two-dimensional medical scans of the patient's anatomyand in some cases complemented with digital photography methods and/oranthropometry databases. Various CAD programs and/or software can beutilized for three-dimensional image reconstruction, such as softwarecommercially available, for example, by Materialize U.S., Plymouth,Mich.

In the preoperative planning stage for arthroplasty, imaging data of therelevant anatomy of a patient can be obtained at a medical facility ordoctor's office, using one or more of medical imaging methods describedabove. The imaging data can include various medical scans of a relevantportion of the patient's anatomy, as needed for joint modeling. For kneejoint arthroplasty, images of all the knee joint and, optionally, imagesof the femoral head or hip joint and ankle joint for mechanical axisdetermination can be taken. An initial preoperative plan can be preparedfor the patient in image space and can include planning anddetermination for joint resections, custom implant design or non-customimplant selection, sizing and fitting and designing patient-specificalignment and/or resection guides and other instruments for guiding thejoint resections, drilling holes for locating pins or other fastenersand for other guidance during the surgical procedure.

Various patient-specific instruments and pre-operative planningprocedures are disclosed in commonly assigned and U.S. patentapplication Ser. No. 11/756,057, filed on May 31, 2007, now U.S. PatentPublication No. 2007/0288030; U.S. patent application Ser. No.12/211,407, filed Sep. 16, 2008, now U.S. Patent Publication No.2009/0024131; U.S. patent application Ser. No. 11/971,390, filed on Jan.9, 2008, now U.S. Patent Publication No. 2008/0312659; U.S. patentapplication Ser. No. 11/363,548, filed on Feb. 27, 2006, now U.S. Pat.No. 7,780,672; U.S. patent application Ser. No. 12/025,414, filed Feb.4, 2008, now U.S. Patent Publication No. 2008/0114370; U.S. patentapplication Ser. No. 12/571,969, filed Oct. 1, 2009, now U.S. PatentPublication No. 2010/0087829 and U.S. patent application Ser. No.12/955,361, filed Nov. 29, 2010, now U.S. Patent Publication No.2011/0071533. The disclosures of the above applications are incorporatedherein by reference.

The patient-specific guides of the present teachings can be made of anybiocompatible material, including metal or plastic. Generally, thepatient-specific alignment and/or resection guides can be single use,disposable instruments made of lightweight materials, includingpolymers. The patient-specific guides can be manufactured by machiningor by various stereolithography methods, selective laser sintering,fused deposition modeling or other rapid prototyping methods. In someembodiments, computer instructions of tool paths for machining thepatient-specific guides can be generated and stored in a tool path datafile. The tool path data can be provided as input to a CNC mill or otherautomated machining system.

Briefly, various embodiments of patient-specific tibial guides 100 forunicompartmental (unilateral or partial) knee arthroplasty for the leftor the right knee are illustrated in FIGS. 1-3. FIG. 4 illustratesanother embodiment of a patient-specific tibial guide 100 used incombination with a cutting insert 200. FIGS. 5-9 illustrate apatient-specific femoral alignment guide 300 and associated instrumentsfor use in knee arthroplasty, including a tibial sizing gauge 400 and atibial clamp or tibial connector 600 for coupling the tibial sizinggauge 400 to a tibial resection guide or block 700 (FIGS. 8 and 9). Afemoral drill template 350 for use with the patient-specific femoralalignment guide 300 is shown in FIG. 10. FIG. 11 illustrates an implantassembly 500 for partial knee arthroplasty. It should be noted thatalthough unicompartmental knee arthroplasty using the devices of thepresent teachings can be performed on either the lateral or medialcompartments of the knee, current surgical practice may be restricted tothe medial compartment of the knee.

Referring to FIGS. 1-4, various tibial guides 100 for partial kneearthroplasty are illustrated. The tibial guide 100 includes apatient-specific body 102 having a patient-specific undersurface orinner surface 104 designed during the preoperative plan to conformunilaterally to proximal and anterior portions of a tibial bone 70(either with or without articular cartilage) of the patient in only oneposition, as shown in FIG. 3. The patient-specific body 102 includes aproximal portion 106 engageable with a surface of a proximal plateau 72of the tibial bone 70 and an anterior portion 108 engageable with ananterior surface 74 of the tibial bone 70. The patient-specific body 102can include a window 103 in the form of an elongated slot. The tibialguide 100 is illustrated on a medial side of the right knee in theembodiment of FIG. 3.

With continued reference to FIGS. 1-4, the tibial guide 100 includes adrill/resection block 110 coupled to the patient-specific body 102 andhaving a drill guide portion 120 and a resection guide portion 130. Thedrill guide portion 120 can be unitarily (monolithically) attached tothe patient-specific body 102 and formed as one piece. The drill guideportion 120 can include first and second registration formations in theform of tapered or cylindrical bores 124 for registration with a tibialdrill insert (not shown, but described in Provisional Application No.61/496,177, filed Jun. 13, 2011, which is incorporated herein byreference). The drill guide portion 120 can also include a cylindricalclearance bore or hole 126 configured to receive and provide clearancefor a corresponding cylindrical tubular of a tibial drill template.

With continued reference to FIGS. 1-4, the resection guide portion 130of the tibial guide 100 includes a vertical resection channel 136 forguiding directly or indirectly a vertical resection, i.e., a resectionparallel to the direction of gravity when the tibial guide 100 ismounted on the patient's tibial bone. The vertical resection can be on asagittal plane. The vertical resection channel 136 can terminate at asafety hole 138 that provides a safety stop for the vertical resection.Specifically, a stop pin (not shown) can be inserted into the safetyhole 138 to limit the depth of the vertical resection and preventover-resection through the vertical resection channel 136.

Different types of guiding formations for the vertical resection areillustrated in FIGS. 1-4, corresponding to different embodiments of theguidance provided by the vertical resection channel 136. Referring toFIG. 1, for example, the vertical resection channel 136 can be formedbetween first and second flanges 132, 134 that extend from the resectionguide portion 130 of the partial tibial guide 100. The first and secondflanges 132, 134 have opposing inner surfaces 142, 144 that are curvedand form a variable coronal width “w” for the vertical resection channel136, as viewed in a coronal plane. As shown in FIG. 1, the innersurfaces 142, 144 are concave toward one another such that the verticalresection channel 136 has a coronal width w (as viewed in a coronalplane) that decreases from the entrance 131 of the vertical resectionchannel 136 toward the safety hole 138. In some embodiments, the width wmay reach a minimum and then increase somewhat before merging into thesafety hole 138. In this respect, a cutting tool, such as a blade orsaw, can be easily inserted through the wider entrance 131 and guidedbetween the narrowing convex surfaces 142, 144 of the vertical resectionchannel 136. A side window 105 communicating with the vertical resectionchannel 136 may also be provided on the resection guide portion 130 forvisualization and/or tissue/debris clearance.

Referring to FIG. 1A, in another embodiment, the vertical resectionchannel 136 may be formed between pluralities of opposite convexsurfaces 145, 147, as viewed in a coronal plane. In this respect, thecoronal width w of the vertical resection channel 136 can increase anddecrease repeatedly in an alternating manner from the entrance 131 tothe safety hole 138. Accordingly, the resection channel-facing surfaceof each flange 132, 134 can be piecewise convex.

Referring to FIG. 2, in another embodiment, the vertical resectionchannel 136 may be formed between pluralities of opposite convexsurfaces 149, as viewed in an axial plane. In this respect, the axialwidth w′ of the vertical resection channel 136 can increase and decreaserepeatedly in an alternating manner in the sagittal direction as viewedin an axial plane. In some embodiments, the alternatingly (in analternating manner) variable axial width w′ of FIG. 2 can be integratedwith the alternatingly variable coronal width w shown in FIG. 1Aproducing a plurality of curved surfaces 141 arranged as cells of atwo-dimensional array, as shown in FIG. 2A.

The alternatingly variable coronal and/or axial widths w, w′ can providea tactile feedback to the surgeon during the vertical resection of thetibia, reduce binding of the cutting tool and reduce heat generationduring cutting. Additionally, the alternatingly variable coronal and/oraxial widths w, w′ allow for tighter tolerances for guiding the cuttingtool.

Referring to FIG. 4, in another embodiment, the vertical resectionchannel 136 can have a constant width “D” in the coronal and axialplane, formed between first and second opposing planar surfaces 152, 154of the corresponding first and second flanges 132, 134. The width D canbe selectively changed to a different and reduced (smaller) width “d” byusing one or more removable cutting inserts 200. Each cutting insert 200can have a U-shape and include an open channel 206 formed between firstand second plates 210, 212 of the cutting insert 200. The first plate210 can have a lesser thickness or width than the second plate 212 forreducing space requirements when placed outside the vertical resectionchannel 136 of the patient-specific tibial guide 100. The open channel206 can receive at least a portion of either the first or the secondflange 132, 134 and supported thereon. In the exemplary illustration ofFIG. 4, the cutting insert 200 is shown mounted on the first flange 132.Each cutting insert 200 can have a different thickness “t” between firstand second outer planar surfaces 202, 204. The distance between thesecond surface 204 of the cutting insert 200 and the planar surface 154of the second flange 134 determines the reduced width d of the verticalresection channel 136. Similar considerations apply when the cuttinginsert 200 is mounted on the second flange 134. In some embodiments, aplurality of cutting inserts 200 having different thicknesses can beprovided in a patient-specific kit that also includes thepatient-specific tibial guide 100. The surgeon can trial and selectintraoperatively a particular cutting insert 200 that can provide asurgeon-selected width d for guiding the vertical resection whencombined with the patient-specific tibial guide 100. The cutting inserts200 can be made of any biocompatible materials, including plasticmaterials and metals. Metal cutting inserts 200 may be selected foradditional rigidity.

Referring to FIGS. 5-8 and 10, an exemplary partial femoral alignmentguide 300 is integrated with a tibial sizing gauge 400 for guidingminimally invasive partial knee arthroplasty (PKA) and determining thetibial gap according to the present teachings. The partial femoralalignment guide 300 is patient-specific and includes a body 302 with athree-dimensional patient-specific undersurface or inner surface 304designed during the preoperative plan to conform unilaterally, i.e., toonly one of the medial and lateral surfaces/femoral condyles 82, 84 ofthe femoral bone 80 (either with or without articular cartilage) of thepatient in only one position, as shown in FIG. 5. The body 302 and theinner surface 304 can extend from a distal portion 312 over one of thelateral or medial femoral condyles to an anterior portion 314. Thefemoral alignment guide 300 can also include an elongated viewing window318.

With continued reference to FIGS. 5-10, an elongated guiding formation308 can extend generally from the distal portion 312 of the body 302.The guiding formation 308 defines an elongated slot 306 with a taperedinner peripheral wall 310 for registering a femoral drill insert ortemplate 350, as shown in FIG. 10. The femoral drill template 350 can bein the form of an insert with an outer tapered peripheral wall 322 thatcan mate with the inner tapered peripheral wall 310 of the elongatedslot 306 for registering to the partial femoral alignment guide 300. Thefemoral drill template 350 can include a number of guiding holes 354 ofdifferent sizes (diameters) and spacing at a patient-specific locationand configuration relative to the femoral alignment guide 300. Aplurality of femoral drill templates 350 with guiding holes 354 ofdifferent sizes and spacing can be provided, as described in ProvisionalApplication No. 61/496,177, filed Jun. 13, 2011 and incorporated hereinby reference. Depending on the procedure, the surgeon can determineintraoperatively which femoral drill template 350 to use and where todrill corresponding holes in the bone for locating and supporting afemoral resection block.

Referring to FIG. 10, the femoral drill template 350 can include a blockportion 356 having an engagement feature, such as one or two outer slots328 on opposite sides of the block portion 356, for coupling with afemoral alignment verification instrument (not shown). Intraoperatively,the surgeon can mount the partial femoral alignment guide 300 on thespecified knee and condyle of the patient in a unique position based onthe preoperative plan for the patient. The femoral drill template 350can be fitted over the elongated slot 306, and holes for guiding pinscan be drilled into the femoral bone 80. A resection block can bepositioned over the pins for performing various femoral resections. Thesurgical technique can then follow standard procedures, such as, forexample, the surgical technique associated with the Oxford® PartialKnee, which is commercially available by Biomet Manufacturing Corp.,Warsaw, Ind.

Referring to FIGS. 5-9, the guiding formation 308 can have a profile ofan open channel or a U-shape with a distal opening 320 through the wall310. The distal opening 320 is configured to receive and engage anextension 410 of the tibial sizing gauge 400. The tibial sizing gauge400 includes a curved portion 402 with a femoral condyle-engagingsurface 404 and an elongated portion 406 that can be coupled to a tibialresection block 700 while connected to the femoral alignment guide 300,as shown in FIGS. 8 and 9. A plurality of tibial sizing gauges 400having curved portions 402 with different thicknesses for determiningthe tibial gap can be provided. A tibial sizing gauge 400 with athickness of 1 mm, for example, can be first inserted into the femoralalignment guide 300 and then followed successively by tibial sizinggauges 400 of 2 mm and 3 mm, if the knee joint tissues and ligaments aretoo lax. In some embodiments, the femoral condyle-engaging surface 404can be patient-specific and designed during the pre-operative plan ofthe patient to mate as a mirror or negative surface of the femoralcondyle of the patient.

Referring to FIGS. 8 and 9, after a particular tibial sizing gauge 400is selected for keeping the knee tissues appropriately tensioned, thetibial sizing gauge 400 is coupled to the femoral alignment guide 300and to a tibial resection block 700 using a clamp or other connector600. The connector 600 includes a block element 610 and a cam device 620with a handle 630. The tibial sizing gauge 400 is coupled to theconnector 600 using a set screw or other locking element 614 that canpass through an end aperture 709 and be moved along an elongated slot408 of the elongated portion 406 of the sizing gauge 400. The lockingelement 614 secures the tibial sizing gauge 400 against the blockelement 610 of the connector 600. The block element 610 has a U-shapedopening 612 that receives a first arm 622 of the cam device 620 of theconnector 600. The tibial resection block 700 can be received in anopening 626 formed between a surface 618 of the block element 610 and asecond arm 624 of the cam device 620 and positioned such that a shaft710 of the tibial resection block 700 is parallel to the long axis ofthe tibia 70. The tibial resection block 700 can be secured with one ormore pins or fasteners 711 passing through corresponding apertures 703of the tibial resection block 700.

With continued reference to FIGS. 8 and 9, after the tibial resectionblock 700 is secured on the tibia 70, a vertical tibial cut can be madeusing the tibial resection block 700 at a location determined by theposition of the tibial sizing gauge 400 relative to the femoralalignment guide 300. In some embodiments, the vertical tibial cut can beguided by a vertical surface 611 of the block element 610. The positionof the vertical surface 611 can be predetermined by configuring thecoupling of the tibial sizing gauge 400 to the block element 610 suchthat the vertical surface 611 is at a preoperatively determined locationon the knee joint for the specific patient when the tibial sizing gaugeis attached to the femoral alignment guide 300. In other embodiments, anindicator of predetermined length can be attached to the tibial sizinggauge 400. The indicator can be used to guide a cutting blade or,alternatively, mark the location of the vertical cut on the tibialresection block 700. In some embodiments, the indicator can be a focusedlight beam or a laser that can project a guiding line of light on thetibia and/or the tibial resection block 700.

The connector 600 and the tibial sizing gauge 400 can be removed afterthe vertical tibial cut is made. The femoral drill template 350 can thenbe inserted into the elongated slot 306 of the femoral alignment guide300 and locating holes can be drilled into the femoral bone 80 throughthe guiding holes 354 of the femoral drill template 400. The femoralalignment guide 300 and femoral drill template 350 can then be removed.A horizontal tibial plateau resection can be made using the tibialresection block 700, and the tibial resection block removed. A femoralresection block can be mounted on the femoral bone 80 using the locatingholes drilled through the femoral drill template, as described in U.S.patent application Ser. No. 13/097,145, filed Apr. 29, 2011, which isincorporated herein by reference.

Summarizing, the present teachings provide various patient-specificunicompartmental alignment and resection guides, drill templates, drillinserts and other instruments for partial knee arthroplasty includingthe femoral and tibial bones. Further, the instruments provided can beused to perform first a vertical resection of the proximal medial tibialplateau followed by a horizontal resection to remove the proximal medialtibial plateau in preparation of a unicompartmental tibial implant.Surgical kits including various combinations of patient-specificunicompartmental alignment and resections guides, femoral drilltemplates, tibial sizing gauges, non-custom resection blocks andcorresponding custom or non-custom implants can be prepared for aspecific patient and surgeon. Non-custom unicompartmental or partialknee implants are, for example, commercially available from BiometManufacturing Corp., Warsaw, Ind. An exemplary unicompartmental implantassembly 500 is illustrated in FIG. 11. The unicompartmental implantassembly 500 includes a femoral component 510, a tibial component 520and a maniacal bearing 530 with corresponding articulating surfaces 516,522 and 532. The femoral implant 510 can include fixation stems or pegs512, 524. Similarly, the tibial implant can include a fixation keel 524.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

1. A surgical kit for unicompartmental knee arthroplasty comprising: apatient-specific unicompartmental tibial guide having a patient-specificbody with an inner surface preoperatively configured to nestinglyconform and mate in only one position with an anterior portion and aproximal portion of a tibial bone of a specific patient, the tibialguide including a vertical resection channel having a variable widthpreoperatively configured for guiding a vertical resection through theproximal portion of the tibial bone.
 2. The surgical kit of claim 1,wherein the variable width varies in a coronal plane relative to thepatient.
 3. The surgical kit of claim 1, wherein the variable widthvaries in an axial plane relative to the patient.
 4. The surgical kit ofclaim 1, wherein the variable width varies in a coronal plane and in anaxial plane relative to the patient.
 5. The surgical kit of claim 1,wherein the vertical resection channel is formed between first andsecond curved surfaces of corresponding first and second flanges of thetibial guide.
 6. The surgical kit of claim 5, wherein the first andsecond curved surfaces are convex towards one another.
 7. The surgicalkit of claim 6, wherein the first and second curved surfaces arepiecewise convex in a coronal plane relative to the patient.
 8. Thesurgical kit of claim 6, wherein the first and second curved surfacesare piecewise convex in an axial plane relative to the patient.
 9. Thesurgical kit of claim 6, wherein the first and second curved surfacesare piecewise convex in coronal and axial planes relative to thepatient.
 10. The surgical kit of claim 1, wherein the tibial guideincludes a drill guide portion preoperatively configured for drillingfirst and second anterior holes into the tibial bone for guiding ahorizontal tibial resection.
 11. The surgical kit of claim 10, whereinthe drill guide portion is unitarily attached to the patient-specificbody.
 12. The surgical kit of claim 1, wherein the vertical resectionchannel ends in a safety hole formed between first and second resectionflanges, the safety hole configured to receive a stop pin limiting adepth of the vertical resection.
 13. The surgical kit of claim 1,further comprising a unitary patient-specific unicompartmental femoralguide having a patient-specific body with an inner surfacepreoperatively configured to nestingly conform and mate in only oneposition with an anterior portion and a distal portion of a distalfemoral bone of a specific patient, the femoral guide including anelongated slot with a tapered inner wall.
 14. The surgical kit of claim13, further comprising a femoral drill template having a tapered outerportion configured to be received in the elongated slot and first andsecond guiding holes configured for drilling holes into the femoral boneto support a resection block.
 15. The surgical kit of claim 1, furthercomprising a knee implant assembly for partial knee arthroplasty.
 16. Asurgical kit for unicompartmental knee arthroplasty comprising: apatient-specific unicompartmental tibial guide having a patient-specificbody with an inner surface preoperatively configured to nestinglyconform and mate in only one position with an anterior portion and aproximal portion of a tibial bone of a specific patient, the tibialguide including a vertical resection channel having a first width formedbetween first and second flanges of the tibial guide; and a cuttinginsert having a first plate receivable in the vertical resection channeland changing the first width of the resection channel to a second widthsmaller than the first width.
 17. The surgical kit of claim 17, whereinthe cutting insert includes an open channel formed between the firstplate and a second plate.
 18. The surgical kit of claim 17, wherein thefirst and second plates have different thicknesses.
 19. The surgical kitof claim 16, further comprising additional cutting inserts configuredfor changing the first width of the resection channel to correspondingand different widths.
 20. The surgical kit of claim 16, wherein thetibial guide includes a drill guide portion preoperatively configuredfor drilling first and second anterior holes into the tibial bone forguiding a horizontal tibial resection.
 21. A method for unicompartmentalknee arthroplasty comprising: mounting a patient-specific tibial guideon a tibial bone; nestingly mating and registering a patient-specificinner surface of the tibial guide onto a corresponding anterior surfaceof the tibial bone and a corresponding proximal surface of a proximalplateau of the tibial bone; and making a vertical tibial resection ofthe proximal plateau through a vertical resection channel of the tibialguide, the vertical resection channel having variable width along ananatomic plane of the patient.
 22. The method of claim 21, wherein theanatomic plane is a coronal plane.
 23. The method of claim 21, whereinthe anatomic plane is an axial plane.
 24. A method for unicompartmentalknee arthroplasty comprising: mounting a patient-specific tibial guideon a tibial bone; nestingly mating and registering a patient-specificinner surface of the tibial guide onto a corresponding anterior surfaceof the tibial bone and a corresponding proximal surface of a proximalplateau of the tibial bone; selecting one of a plurality of cuttinginserts having different widths; inserting a plate extending from theselected cutting insert into a vertical resection channel of the tibialguide; changing the width of the vertical resection channel to a reducedwidth; and making a vertical tibial resection of the proximal plateauthrough the reduced width.
 25. A method for unicompartmental kneearthroplasty comprising: mounting a patient-specific femoral guide on afemoral bone; nestingly mating and registering a patient-specific innersurface of the femoral guide onto a corresponding anterior surface and acorresponding distal surface of the femoral bone; coupling a tibialsizing gauge to a distal opening of a guiding formation of the femoralguide; measuring a tibial gap; coupling a tibial resection block to thetibial sizing gauge; and guiding a vertical resection of the tibia atdistance determined by the tibial sizing gauge.
 26. The method of claim25, further comprising: removing the tibial sizing gauge; inserting afemoral drill template into the guiding formation of the femoral guide;and drilling locating holes into the femoral bone through the femoraldrill guide.
 27. The method of claim 26, further comprising: guiding ahorizontal resection of the tibia using the tibial resection block.